Lakeside Machine LM-7

The "LM7" is a Rimfire Feed System (RFS) conversion for the AR15/M16 family of firearms.

LM7 History
In mid October 2004, Lakeside Machine was asked  to develop a rimfire belt feed system that would accommodate the common lower receivers of the AR15 and M16 style of firearms. On November 26th of 2004 the LM7 was revealed. The LM7 was created using the proven technology found in our Browning miniature and Vindicator line of products. To the best of our knowledge, this rimfire feed system is the only select fire capable rimfire beltfed in the world. The LM7 will be sold as a TITLE1 firearm.  It will be treated as a regular firearm receiver and a 4473 and NICS check will be done by the transferring dealer. Until other United States Government status can be obtained, the LM7 will be sold in this manner.

LM7 Features
The LM7 is made of steel and its durability is paralleled to the Browning miniatures that have been built by Lakeside for years. The design is robust and strong and will take tens of thousands of rounds with minimal wear. Higher wear parts such as springs and firing pins will be inexpensive and easily replaced by the user.

The LM7's hand guard mount system is identical to the threads found on military spec upper receivers. Virtually any hand guard known that fits current AR15 uppers will fit the LM7. This versatility enables the LM7 to be fitted with clam shell style hand guards to the free floated and the latest Picatinny rail systems at any time.

The barrel shown on the prototype is 16.25" with 1/2-28 threads for all common muzzle attachments. The production models will incorporate a quick change barrel system for any barrel length or configuration desired. The barrel will also have a front sight block with weaver compatible rails for accessories and sights.  The upper is chambered for 22LR but 17M2 can be used with a barrel change, no other modifications are needed to run .17M2 ammunition.

The top cover release lever (left side of the receiver in front of the scope mount) is also a bolt hold open device. The bolt hold open feature can be used regardless if the top cover is open or closed. This feature is very handy for clearing the bolt face and breech area of dirt and carbon build up and also for clearing the last spent cartridge from the t-slot in the bolt face.

The rear of the LM7 upper is machined so any weaver adaptable optic sight can be mounted. Eotech and other electronic dot sights are very popular and work well with this style of mount system. The rear weaver base can also use the clamp on iron sight systems commonly found on the open market. The quick change barrel system will have a front sight mount to match the detachable rear sight assembly.

Modifications are needed to use the LM7 feed system on your AR15/M16 lower receiver. The energies from a rimfire are tremendously different than those for a centerfire cartridge. The LM7 is a blow back operating mechanism. The limited energy of the 22 LR is used to accomplish the entire cycling process and advance the belt for each cartridge.  All factory centerfire buffer assemblies must be changed from centerfire to our LM7 buffer designed for these rimfire energies. The LM7's buffer is also a safety feature with this unit. With Lakeside's rimfire buffer installed you will not be able to operate any centerfire upper if attached.

Each upper feeds ammunition from our woven fabric belts or our exclusive Nylon disintegrating links. A loaded belt is fed directly into the upper or out of the belt box. The spent cartridges are expelled downward though the magazine well. The empty brass can be caught in the "magazine body" or the floor plate can be removed to let all brass flow right through. A link recovery system is going to be integrated into the belt box/brass catcher system.

Photo and information from: Lakeside Machine

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